Common-battery automatic telephone system.



T. G. MARTIN. common BATTERY AuToMATlc TELEPHwNE SYSTEM. l APPLICAION FILED APR.9| 9I6- l Patented Apr. 24, 1917.

2 SHEETS-SHEET l.

LG. MARTIN. COMMON BATTERY AUTOMATIC TELEP10NESYSTEM.

2 SHEETS-SHEET 2A my invention ooi' is a. diagru.mimito UNITED oimito PATENT oFFIoE.

TALBOT G. MARTIN, F (.lIlLClAG, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, T0 AUTOMATIC ELECTRIC COMPANY, CORPORATION OF ILLINOIS.

CMMON-BATTERY AUTOMATIC TELEHONE SYSTEM.

Specicetion of Letters Yatent.

Pute] lted Api?. 24, 1917".`

Application filed April 9, 1906. Serial No. 310,855.

uit n of the iiteol States ol America, und reel( it oil (lhlohgo, Cook county, illinois,

tion is; the provision of :in improved nml highly eilieient oonnnon. buttery automatic tel lshone system.

' il objects :ire the provieion of en irn- )roved const nothin. :ma exigeaient ivhelfm liy the eminent for tel pmposee ie fed to the llingl oi emite tin-oooh eeiftein colle oi wimlinge oil the oonneetme oi" elw'itehing nino-hin hy Whieli commotion le einnpletefl dil'iectly with thc .lineso the milled silhsl'u'ihers; the proifieion of :in ilnjgn'oved con.- struetion l intl n 171,11 n gement where] Witohing` v supplied to the. i 'xii' e lines v "1- teiy or` other suitzihle eentifnlized somme of elzu'rent sujmi'ly, end whereby Clillfelentiel :intl }.)ole-eh"1n invii` rel-.i eine :ulivi n taeeously ein ployed in the .unueetoi'e to ou switching operations, sie well :le the Supply of talking culi-lient to any und. :ill unporerily established talking eiirenite; enel the pro vision of eertoin details; and lhzitii'i'ee of improvement, irlflpioved. eii'euit :iw-:i and. Goinliiin tions tennliw to in' general ellieieno jiy a. telephone system ol" tl' ter.

To the foregoing und. otl' e." iii eet forth and el:

In the unzeompiin Y rep ire. .cl e

cuits., sllb-etzitione ing :ufraligelnei'ito Station #100, "for i tion with the euh J0; z" fill be. seen. that the oentl'el e'oijmifmiie eompriei. among other things the first-selector A. .and

i central o1' common battery Bv for supply ingoll ehi-rent, the co1 ineetm' C and the iii-.eb selector A? ol the call ed line.

Fig. 2 .il persi Ctf Ye diuglnnilnutie View of the Connector Sivit( h C. u

Fig. i udiagl'unn nitie View showing the additional iele:1se-ci1,ulits en'ililoyed when l1 stimuli-selector is yne( d in addition to the Iimtelectors and co1 nectoi'ftV .shown in the to ite i'ioi'niel posigtioi' in :i clockwise direc-` tn` while :it the sulz-etntiiiin .#5220 the. opeiwltione are. perfornwl in just exil-e ly the olijmeite cliteetion. The siili-slziltion #100 is oi' the wel'l-klnimn ty )e in which a switehhook i2 that is pivotecl :it :1 point 3 is provided with e. nnn'i'oei' of anni Ll, 5 and 6 foi;- Controllir t the .s h-stiition eii'ellits. The Saidk switch-hook is nolfn'izllly retained depiessefl in. e. position Shown :i t sub-station #220 by the, receiver 7.. hut when the reeel el ne moi'eil the. seid Switch hook, by the lower of not showin Sesto a. position indi.-

et the. s1ili -stnt on #10G Neer the il ol. the so-eaflle(, keyhfmigd or stilistation n'leizhoniem a. shaft '8 is located: :it right singles theretlin sind' su )poi-ts :if Somenll'ed iinpulsemheel S9 secured to seid shaft-rigidly. Seid impelee-wl'ieel is [nrovidecl with a. numbei.L of liieiipheirfzil teeth l() which :we eclnptecl,

when: the seid dial is totalled in .1 fleft-lnmd i noukiewheel the switch-hook-the cam-arm 54 is in engagement with the ringer circuit spring 15, thereby establishing the ringer circuit through the ringervl across the subscribers line. Under such conditions, as shown at `sub-station #220, the springs 17 and 18 are. pressed apart, as well as the springs 19 and `20. The former two of said springs control the continuity of the secondary circuit that includes the secondary winding of thesubstation induction-coil at the sub-station #100, while the latter two control the continuity of the primary circuit through the primary winding of said induction-coil, and through the subseribers transmitter. Upon the same shaft with the impulse-wheel 9 there is a member or cam-dog 21 that works in conjunction with a lock-cam 22 to so lock the dial that it may not be turned while. the

receiver is on the switch-hook. When the switch-hook 2 rises the cam-arm 6 raises the locking-cam 22 until the insulating tip 23 nearly clears the'hooked end of the groundspring 24, which latter it controls with respect to the sprin 25. But the said insulating tip does not all behind said locked end until vthe dial is pulled around the first time, at which time the pin 26 on the end of the cam-dog 21 drives the lock-cam 22 up a little farther,.atwhich time the ground-springs 24 and 25 come into contact. Attention 'is called to the fact that the finger 27 of the cani-dog 21 (whenever the vdial is out of normal position) leaves the spring 17, which latter then by reason of its own tension withdraws' from the spring 18 and opens up the primary circuit, 'thereby disconnecting one side of the subscribers line from the other.

`The sub-station is provided with three socalled release-springs 28, 29 and 30 which are so controlled by the cam-arm 4 that when -the switch-hook descends the said releasesprin are forced into contact for a moment and t en disengaged; but when the switchvhook rises the said springs are not Vforced into contact. This is accomplished by means of parallel projections one of which is located upon the release-spring 30 and the other upon the release-arm 4.` These projections are somewhat fiat in structure and mounted at an angle, :so that the under edge of the flange on the arm 4 in descending Ipasses to the left of theupper edge of the flange on the spring 30, forcing the springs 30, 29 and 28 into contact; but when itis rising the upper edge of the former flange asses to the right of the lower edge of the latter' flange. The substation #100 is further provided with a signalingor ringingbutton 31 which controls a signaling-spring 32 with respect to the contact-points 33 and 34. There is also a condenser 35 in the secondary circuit, which will bedescribed hereiii-after. It will be noted'from the preceding that" the ground-post 12, after the switchhook has been raised, and the dial rotated forward, is connected to the round terminal G1 through the ground-sprmgs 24 and 25. The first-selector may beof any suitable, known or approved construction. .The firstselector switch A shown in Fig. 1 is ofthe general type ofselector switch disclosed in United States Letters Patent No. 815,321, granted March 13, 1906, to Keith, Erickson and Erickson, and comprises the usual mechanical details and circuit connections.

The connector 'C is of a particular type, being a common battery connector and provided with suitable relays, operating magnets, and circuits to be hereinafter described. The connector and vfirst-selector are very similar, but in the provision of relays and circuits the two Said switches are generally different. Like the rstselector A the said connector C is located above the line and private banks 148 and 149, respectively, with which .the switchshaft-wipers 150, 151 and 152 respectively engage. Thesaid wipers, as in the first- Selector, are mounted upon a switch-shaft 153, which shaft is, in addition, provided with the usual cam 154, longitudinal teeth 155, circular teeth 156, nbrmal-post-arm 157, and coiled spring 158, the outer end of which latter is attached to the normalpost 159. The circular teeth 156 are traversed by the usual longitudinal vslot 160 in which the shaft-rest 161 operates. The connector-switch like the rst-selector has'two line-relays, the vertical-line-relay 162 and the' rotary-line-relay 163. These two relays between them and by means of their respective armatures 164 and 165 control the so-called line-relay-springs 166, 167 and 168 and in addition the trunk-release springs 169 and 170. The vertical-magnet 171,/ the release-magnet Y'172, the rotary-magnet 173 and the private-magnet 174 are severally'- similar to those described` in the firstselector and perform similar functions. The release-magnet 172, however, as distinguished from the release-magnet of the first-selector, has its armature 175 located on the right side instead' of -on the left. Saidarmature is provided withan elongated member' 176 for controlling the double-dog 177 at the release. Said double- 4dog is familiar and the exercising control of the said release-armature 175 will be hereinafter described. 'The releaselink 178 of the connector, unlike the release-link of the first-selector, is permanently 'fixed by A the pin 179 to a suitable part of the switch. Normally said release-link has a downward spring tendency and acts as a latch for retaining the double-do 177 normally disengaged from the swit'c -shaft 153, at which time the upwardly-projecting pin 180 upon the upper side of the body of the double-.j l'dog 1 is retained within the aperture' 181 dri m1' i,

nlw-relaLy-Sprng (i and ont@ the mid Sprin n t@ the grounded A y While: til l, Spring 100 m" 'ximacwl t@ 'the nun- ]3, The cirtroy, "Munition bealse-*n'lzlgnet 105 wy n'xagnet the 11011m .iO with. two J e tem'ni-- "1. ,L ed with mi? Mm Winding 214;,

erate for the digit 2, rmovcs his receiver vfrom the switch-'hook and then places his lto correspond with the digit 2. The dial is then permitted to rotate back to normal position, which it does under the force of a suitable coiled spring usually provided in a telephone of thetype shown in Fig. 1.

' Again' the dial is rotated to correspond with the second digit 2; and for a third time the calling subscriber, by inserting his finger in the dial-hole mimberedO, rotates said dial .bringing it into connection therewith. Im-

mediately after, the lugs 1 0- upon the opposite side of the impulse-wheel 9 in a similar manner act upon the vertical impulse-finger 11. For the first 'digit (the digit 2) only two of the impulse-teeth pass to the rearward of the vertical impulse-finger-lug 227, and when the dial is returned to normal position the vertical impulse finger 11 isy pressed onto the ground-post 12 once as the tooth 229 passes across the lug 227, and once as the tooth :230 passes across. the said lug; and immediately after the rotary impulse- `finger 1,4 is pressed once onto the groundpost 12 by the rotary impulse-tooth 13. In

until his finger strikes the finger-stop, after which it is permitted to again return to norf mal position. The first operation of the dial, in a manner to be described, operates the first-selector A and causes t-he latter to select a trunk-line to some idle connector, designated in Fig.V 1 as connector C. The second and third operations -`ot' the dial operate the connector to cause it to connect the line of `the calling subscriber with the line of the called subscriber, after which the latter may be signaled by the foriner pressing his signalinguttcn. When the calling subscriber removes his receiver from the switchhook the cam-arm 5 leaves the `spring 15 and destroys the circuit through the, ringer 16 and at the same time permits the springs 18 and 20 to rise until they close contact with the springs 17 and 19, respectively. At the same time the cam-arm 6 raises the lockingcam 22 to a point that will permit the pin 26 upon the end of the cam-dog 21 to clear the locking-cam 22, when the dial is rotated, but not sufficiently to cause the insulating tip 23 to clear the angled section upon the ground-spring 24, so that even after the switch-hook is raised the ground-spring 24 is kept away from the ground-,spring 25. But as soonas the dial is rotated in a counter-clockwise direction the cam-dog 21 raises the locking-cam 22 to a point at which the vinsulating tip 23 clears the angled section of the ground-spring 24 and thereby causes tlie ground-spring 24 to come into contact with the ground-spring 25. A t the same time the finger 27 upon the cam-dog 21, being removed, permits the sprin s 17 and 18 to separate and thereby brea the connection between the verticalland rotary line-conductors 225 and 226.- -The lugs 227 and 228 upon the vertical and rotary fingers 11 and 14, respeqtivelyfare twisted at an angle and retained in such a position that'as the dial is rotated in a counter-clockwise direction the advancing edge of the tooth 13 upon the impulse-Wheel 9 clears'the right-hand edge of the lug 228 and strikesl the said lug 228 at about the middle portion and then drives 1t away from the ground-post-12`without this manner, and since the vertical impulsefinger 11 1s connected with the vertlcal-llneconductor 225, and the rotary impulse-finger 14 connected with the rotary-lineconductor 226, at the return motion of the dial the vertical-line-conductor 225 is given Vtvvo ground impulses and the rotary-line-conductor 226 one ground im ulse. It is for the purpose of preventing tie indicated ground impulses from passing from the vertical to the rotary line-conductor and vice versa thatk the springs 17 and 18 are separated While the dial is out of normal position. Each of the electrical ground impulses thus given the vertical-line-conductor 225 energizes the first-selector vertical-line-relay once. The current each time passes from ground 'G1 through the ground-springs 24 and 25 to the ground-post 1 2, thence to the verticalline-conductor 225 and through the sideswitch-Wiper 130, contact-point 136 and to the vertical-line relay 55, thence through the bridge cut ofi' relay springs 65 and i 66 to the batterylead 233, and tothe nongrounded terminal of battery B and to ground G. Thecvertical-line-relay-armature 57, being attracted, forces the linerelay-spring 59 on to the ground-spring 61, energizing the vertical-magnet 71. The curfroml ground G2 through 'the line-relaysprlngs 61 and 59, private-springs 114 and 113 and vertical-magnet 71 to the batterylead 233, and to the non-grounded terminal o f battery B and to ground G. The first 115'" tlme that the vertical-magnet 71 is energized it attracts its armature and raises the shaft one step, the shaft being retained in its ralsed position when the vertical-magnet 71 becomes denergized. The second time that the second level o the line-bank, the privatey Wiper 41 op osite the first contact of the sec- 'rent in this last energizing circuit passes 3' ondlevel o the private-bank. Being thus'- raised the shaft is in a position to be rotated as soon as the rotary- 1 ne-'relay -56 is enerfinto thirl position. l sido-swfltoh talma phlc'so wat ba'loi mamon gized. The onargization of said rotar-alinerelayoccnrs as soon as the rotary-linmiondllctor is groundett The current in the en.er,'izi1g`cni:liit through the rotary-Hna relay 56 flows from the ground terminal (t1 through the grountl-springs Z--l and to the gronnttpost 12, thence through tha m tary impulse-finger 14 to the rotarylinecondactor 226 title-switoh--Wiper 131, conn tact-point 137, the rotai'y-lii1e-1ala},f tllrrnlgh the bridge-ontot-r@laysp1'inga (a4, 65 and ttto thv battery-laad 2351? and to.` the non-gronmleil terminal ot battery I3 and to ground (l. Being enargiaafl the rotary-Hna relay 5 attracts its al1-maturo and tharoby at s the lima-relay. wiring (S0 to ha forced mto Contact with tha @wound-spring til for a moment. The privatamagnet 10S iatliaraby' enargltal` over .a circuit in which ouvrant flows from glolvlntfl (il-2 tl'namgh the `linoira-` laytprings 0,1 and 60, and privata-maf 108 to the battery-leal 13th y'to tba n m grounded terx'nnal battery B 'anti to ground Gr. The privatwnlagnat being amr gized and (lanergimd, immediately after, the siclewswitoh passes to second position, dascribed, and aS a result tho "rl wiper 128 engages the grmlintlatl contact-point 138; `At anna the rota net 9411s energized andthe energizing oarrent flows from ground G3 `to tho siflaawfltoh col'ltact-point 138 and through the sitio switch-Wiper 128, and rotarymnl(Tnet-coil 91tin series with tha intarruptr-sl. 'ings 'l0-'t and 105 to the nmtgriinxnflecl terminal ot' battery B and to ground Gv. The rotary magnet 94 than attracts the rotaryarmatnra 97 and causes the sl'iat't to be rotated, ana slaap.` It will be understood that just about the, time that the rotaryarmatura ll atrilcaa the rotaryl11agnet poleqpiaces t m (log falls behind the Hfst of' the langt minal. taath to prat/ant the shaft from returning; to normal ,a'isitioifl when the, rotanti-i'napfnat ba comes t enorgized at'tha il L'ltalat that tho interruljiter-finger forces tba batteri-antarsprings 104 and, 105 apart and thereby la stroys thev energizing 'circuit through said, magnet. The said intrruptibn omni inst at about tha timol that thv rotaryarim strikes the rotary-magnat polonia@ l the rotary armature rotates tha a. the Sama time depressas thalprirata armaN ture and` 'carries it down 'until the ahaift- Wipers 39, L'10 and 41 aro rojtatocl onto tlm first level of their respurtiw, hantai. soon the Circuit tl'n'ongh tha rotary-ina@ net 94 is intarraptod tlia rotar armature begins vto return tcl its normal ya sition, and th' ,privataarlnatnr aa lia-fll, tha latter tot lowingrup the mcorlln i'novanwnt ot thcy ro-y tJI'V-ayrrmatylte, and tho aiilr'sewitoli apn-intra The 'shitting of tho .lio intra*- t i n tarrl lijntm'- pintar-finger i'iarraita l nartewl ana til `thal una 'tbn saoonfl laval, but 'in energizing (irenit that has been desfcribedA through the rota:r}.*-niagnat is destroyed at tha point ha wenn theI side-switcl1-\vipar 128 and the cont let-point 13S. 1When the motion ot" tha rota ry-arn1atnm 97 ceases perma-` nently the calling operation of the' first-Selaotor cornes to an and. The line-wipers have than Seized lpon an idle twinklinel sin'lilar to tho trank lino tha conductors 24;() and 241 of whirfh ari shown and which lead to anitlla com-molar. lTha said soizetl trunk is protected fran further anima-ahy a guarding potenti il that established at the privata-wiptr 41 ai'nfl, than` om, iat "all @thor ,privatabankf: 'rntaets connected. in rnizlltiala thereto. Saixfl gnartfling potential blislioll by raasono'f Coni'icction ben ther g1" aand tarn'linal of battery B and 1a con mt and way of the ground t rminal (.l", sida awitcltwiqjier 129, backxelaaaarolay "T4 oondi'xatfn 21113 and private- 'l t will ne notictal that tha sub- QZli and 226 that tarrai'r'la n tha sift, mtoh,--wf ira 130 and `llfl"lm'rr a r mplo ol lrails '24:4 and 245 con aitlauot the, lino and the othar 'to f ha other ,i ol lima Those ofmtlantors ill-.el anfl l are nown aa the vlilianornntl-ionrnrtnra and tar llnata 1n connector lin aba n (intacta tha t (a'riespond to the minibar ot" tha subscriber #100.

That@ is also a thirdv conductor Q40 tlm-ttm'-l n'i'll'lat'ta in tll Swittvlrapring fr?, a ml iaknown aa the nrivtlt .1,-1ifni'mil-Contlactor. W han tlm tirant-Salomonshaft is raiswl thvI Saal Sp1-lng engnigaa th@ apr-ingr 54 whirh ronnvctml to tha gianni-(l Prnlinal tl, and as a rrsult a gnartli of pttantial (i llllishnfl ovm' they aaifl privata ni'lrlnal to tha fronmotor pribanlt'luiitaot that corraapom'la to tha tarrr'iil'nlla of tlm anbacrib 1r #100. The a gaarl'liitrymtantial la" ,a tima estabn hahntl, no ra l' f "bearilmr may', aawill he Dointatl ont, ronaornt with thv Calling!1 lima. In the` Hanau waltY that tho tiralaei-,lwftor hasmalla tlm til-f t 'trnnlt-lii'm 'busy by iirlaoing a glmrtlibg pofmitial at tlm lilat {navata-banli- 'rlaaitaa-,t ot tha actoral laval of tha privatw baalt, otliar pritata-hmili'rontacts may be nnatla bij y'bj" otlwr first-F lautols. lnt if at, tha wtinxaa that tlm walling; sul'isoii'iber :#100 grounds tha rotary-lna-oomlnctmand shifts tha fir: baalt-atolaitlo-awitah to second 'maitimi, aa t asmilaal, tho first nino privatolamlt-oont; ,t i oll'tlsa nunmal laval. of the, pri- -aatabanlt am than busy, tha first-Selectorahalt will nrt stop, dasafribafl, when the wiigirora ara 1i: aantal onto the first Contact of ,aarfl thv private,- inaanat will otain tha ,-awitoh in ancond 'y'iostif: nntl th ahaflt--wipara ara mutated 'liirw'mnl- :lin iirat nina lnlay contar-,ts and, l, lawol"mln on :o ywith ofn'itart. The first ainay contacta lar/ing gronll'ltletl, thon when the the rotary-magnet 94 being closed, at the juncture when the side-switch-wiper 128 engages with the contact-point 138, the rotary armature 97 is then attracted by the rotarymagnet 94 andy the shaft rotated one step. The line and p rivate wipers 39, and 41 are, therefore, carried into engagement with the first terminal of the second levcl of their respective banks, and at the same time the private-armature 107 is depressed by the rotary armature, and the interruptersprings 104 and 105 (at the end of the stroke) are separated by the interrupter-finger 103. There being a guarding potential at the first contact which the private-wiper 41 meets af circuit is completed through .the privatenagnct 108 which extends from ground tcrminal G of battery B, through'the privatewiper of whatever' litt-selector is occupying the first trani; 'of 1e second level, and through .thelbank-miiltipling-conductors to the contact-poi'ntr with' which the private-v wiper is in contact, through the privatewiper 41, conductor 243, back-release-relay 67, side-switch-wiper 129, contact-point 139, privatemagnet 108 to the battery-lead 233 and to the non-grounded terminal of battery B and to ground G. The private-armature 107 is therebyrretained in Aa depressed condition even after the rotary magnet is denersrized and the side-switch is held in second position. The side-switch-wiper 128 being, therefore, retained in, engagement ywith the grounded contact-point 138,7as soon as they interrup'ter-springs l104 and 105 ref -ngage,' the energizing circuit through the rotary-magnet 94 is completed once more. As a result the rotary-armature 97 is again attracted, the shaft rotated one more step, and the private-wiper 41 slides onto the second terminal of the second level of the yprivate-bank. Said second contact also tact the private-wiper 41 is rotated one being grounded the energizing circuit through'the private-magnet 10S is still maintained, so that the side-switch is still held when the rotary-magnet 94 is again denergized. Clearly, then, the shaft will be rotated in a step-by-step manner as long as the private-*wiper 41 continues to encounter grounded private-contacts. After being rotated onto the ninth conmore step into engagement with theI tenth contact of the second level of the privatebank; but this last contact being devoid 0f guarding potential, the energizing circuit through the private-magnet 108 (which has up to this time maintained the private-magnet energized) is broken. This occurs at just about the time the rotary-armature 97 is at the end of its attractive stroke, so that the private-armature that has up. to thistime held the side-switch in second position through the medium of the magnetizing force that has now disappeared fromv the nivate-magnet falls back as the rotary-arthe contact-point 138 occurs just before the intcrrnpter-springs 104and 105 rengage,

and then thcV circuit through the rotary-v magnet 94 is permanently broken aud no further rotation of the shaft can take place; At the same time the engagement of the side-s'uf'itchnviper 129 with contact-point 143 provides the private-wiper with guarding potential to protect the trunk seized by the line-Wipers 39 and 40. Having seized this trunk and, therefore, the idle connector C the callingsubscriber #100 operates his dial for the second digit 2 of the number220.` Again, as the dial returns-to normal position, afterhaving been advanced, the vertical-line-conductor 225 is grounded twice and the rotary-line-conductor 226 once. Grounding the vertical-line-conductor, now that the subscribers line is-extended to the connector C, energizes 'the connector vertical-linevrelay 162. The said vertical-line-conductor being grounded twice the Said vertical-linerelay is energized twice and `in each case the energizing current passes from the ground termina-l G1 at the sub-station #100 to the ground-post 12'and through the vertical impulse-finger 11 to the vertical-line-conductor l225, thence through the first-selector side=switchwiper 130 to the contact-point 144 and over the conductor 248, vertical-v line-wiper`39 and vertical-trunkfconductor v240 to the veitical-line-relay 162 and thence to the conductor 249 and through the polechanging-relay-sprin 215 and 216 to the battery-lead 233 an Vto the non-grounded,

terminal of battery Btand to ground G.

Being energized twice the v'ertical-line-re-y lay 162 presses the verticitl-line-relay-springs 166 and 167 into contacttwice through the medium of the vertical-line-relay-armature' 164. An energizing current 4flows through the line-relay-'springs 167 ,and 166, conduc- 130 -in shifting: its' p when het, 171. 1.10 1th., @uw the.: crmlt-mntuwl 21,9 to the, Mlm grounded wv. gvounrji G, y tmiuiating its :9. magnet is 4 "L77 t0 bu re switclirs am "t positinm if; i :md heldm SIL IW with the brummt-lvm.w with the #nimmt-p fm, internal (Lm-fwn' im the .mzirm--Hun grmmc'ld again. tlm stead 0f th@ v gi .glad when t1. xehyy--sm'in "27 5 extends romthe ground terminal G at ,the connector side-switch to the contact-point 268, side-switeh-Wiper 261, private-wiper 152 and private-normal-conductor281, and

ima A' 4cal ed line is ing subscriber grounds theA rotary-line-conthrough the switch-shaft-springs 282 and 283 to the bridge-eut-of-relay 275 and thence to the battery-lead 233 and to the non-grounded terminal ofl battery B and to ground G. Connection between the calling and called line having been established the calling subscriber is in a position to signal the called line by pressing his signaling or ringing-button' 3,1. But before proceeding 1t be explained that if for any reason the busy at the time thatthe callductor 226 for the last time, as explained, to transfer the connector side-switch from second to third position, and to complete the connection, the connector C is thereby released. For instance, if theline ,#220

`Aduring the busy has been called by any connector there will be a guarding potential at the 'tenthprivate contact of the vate-bank149 corresponding to the line of thesub-station #220. Or, on the other hand` if the first-selector A1 of the. called line is being used the said private-contact will be connected to ground from the instant that the switch-shaft is raised one step. Said guarding potential will reach the Connector private-bank 149 by way of.

the private-normal-conductor 281. At any rate if the private-wiper 152 finds a guarding potential at the tenth contact of the second level of the private-bank 149, when the calling subscriber grounds his rotaryline-conductor 226 for the last time, instead of the side-switch .being trippedl to third position the connector will be released. This occurs because the private-ma becoming energized, as the` nal result of the calling subscriber grounding his rotaryline-conductor 226, completes an ener izing circuit through the release-magnet 1 2 of the connector when Athe armature 260 of said private-magnet 174 forces the privatesprings 199 and 200 into Contact. ergizingcircuit for the release-magnet-172 release extends from the ground terminalG 'of battery B to the tenthcontact of the second level of the connector private-bank 149 through the private-wiper 152, conductor 284, side-switchwiper 261, contact-point 264, conducto!` 285, private-springs 199 and 200, conductors 286 `and 287110 the release-magnet 172, thence over Qne of the main objects Vin thusl dlsconnecting the said line-rela second level of the pri.

et 174 upon` is energized as a the conductor 259 and circuit-controllingsprings 218 and 219 to the non-grounded terminal of battery B and to ground The connector release-magnet 172 being enerzed the release-armature 175 strikes the double-'dog 177 to the right of the bearings,A so that the lug 180 is caught and held in the aperture on the end of the release-link. As a result the switch-shaft 153 is left free to rotate under the infiuence of the coiled hind the rearmost lower tooth 192 and retained there until the connector is used again.- It will be noticed that the restoration of the switch-shaft begins even while the release-magnet 172 is energized; but since the energizing circuit through said release-magnet comprises the private- Wiper' 152 and side-switch-wiper 261, it is evident thatv when the shaft rotates back toward normal position, and when the side-switch-wiper 261 is -forced away from the contact-point 264, the energizing'crcuit will then be -destroyed at two points, at which time the connector release-armature regains its normal positon. Thev calling subscriber thinking that he has established connection presses the signaling-button 31, with the ,result that the vertical-lne-conductor 225 is grounded. This produces, o'E course, an energizat'ion of the connector vertical-line-relay 162 in the usual manner; and since the connector side-switch is in first position the relay 162 produces in, turn the energizing of the vertical-magnet 171, through a circuitthat is already familiar, when the line-relay-springs 166 and 167 are pressed into' contact. The ground connec-v tion between the vertical-line-conductor 225 When the release-armature 175 roand the ground terminal G2, when the sigvThe vertical-line-relay 162 of the connector the vertical-magnet 171 result and the shaft is raised so that the springs which it controls through the medium of the normal-post-arm are brought into contact. When the saidY springs 293 and 294 come into contact a C being energized busy signallinglr eirouit established through the receiver 7 of thv callin;T subscriber #100. A busy signaling rurrvai that is induved. for instaure.. in a swoiular) winding 2115 ot the inf'lnvtion-roil 200 liasses lroln said voil 205 through thv su'itvh-shaft-springs 202% and 2.0ito thv rontart-point QUT oi the vounector sidv-sn'itfh and through thv 4sideswitvh-n'ipvr 200, ringvr-relaysprings 20T and 209. ronduvtor 1' rondvnsvr 272. rotar \'trunl.r:oudurtor lll. rotary-linv-wiper 11001' thv til'Stsvlwtor rondurtor 250. vontavt-polnt 115i, sidv-s\\'itch-wiper 131. rotary-linv-vonduvtor 220. primar)y winding 291) ot thv imluol,ionroil Z100 and transmitter 2101 to the rvrtival-liue-ronduvtor 225, firstsvlvvtm sidv-su'itolrwiper 1510. altari-munt 144, cozuluvtor 21S, vertical-line-wiper S19, rvrtiraltrunlt-vond'uvtor 210, rertiraldinerela)` 102, polo-changingrelay-springs 215y and 210 to tho haltvi- V-lead and bavl: to the coil 205. The vallinlLv suhsvrihvr .#100 learning". therefore, that the dvsirvd linv is bus-v will then restore the rvcvirvr T to the switvhdioolc` `@rounding thv rvrtival and rotary linv-vomlurtors 223 and 2213 .simultaneH ously. This is dono when the release-vani 4 foroos tho release-Springsitl, 29 and R0 into contact. '.lhey conz'leetion from round G1 to thtl rortival-line-vonduc'tor 22:1 voniprises the gronmhsprings 24 and 25, Conductor 292, ground-releilse-spring S0, rvrtiral-r Mase-springr 20, which latter is vonnevted to tho vortical-li11ooo1uluvtor 225. The. ground connection to the rotary-line-vondnvtor 220 is established from the said ground GL through the ground-springs 24 and 25 to the ground-roleasoslning 30, thence. through the sln'ix'lgrs 20 and 2S to thv rotary-lineconductor 220. Both of tho line-conductors being grounded at the saniv, timeI the, vertical and rotaryy lino-relays 102 and 103 of the oralnootor areenergized at the same time` and as a. rosult the trunk-rvloaswsprings 100 and 170 are brought into Contact and an energizing circuit is thereby established through the. connector release-magnet 172 and the first-selector lmolm'elvaso-relay 67. The energizing current in this caso passes from' ground Gr'1 at the.V firstselector side- -switohto the contact-point 143, sido-switch- Wiper 129, lmoh-ieleaso-rolay 67, private- .Wiper '11, triInhrelease-conductor 302, trunki'eloaso-sprlngs 100l and 170, release-magnet ground (l.

172, oil-ouit-oontrolling-relay-springs 218 and 219 tothel battery-lead 233 and tothe non-grounded terminal. of battorfy B and to The connector release-magnet 172 upon attracting its armature 175 Causes the connector' switch-shaft to he restored. At the saine time that the, connector releasemagnet 17 2 `isnlagnetized the `first-selector back-release-relay attracts its armature 68 and forces the hach-release-relaysprings 69 and Minto coutart, and as a result the first-^ selector releaseam griet 81 is energized also. 'lhv energizing vir niit through the said firstsvlevlor release-u1: nvt S4, thus estal'ilishvd, permitsl energizing' current to lion' from the lIround terminal G through the track-re lvasv-relay-springe (30 and 70 to the releaseniagnet 84. thence to the non-grounded ter` ininal of battery l and to ground G. The, i'vlease-n'uignvt Si :hon attracts its armature, thrusting the rrlease-link forward and latohing the double dogr tlierewith. 'hen thv subsvrihes switrh-hook 2 desvendssullirivutly to allow thl roleasosprings 28,20 and $30 to again svprrae, the energizing circuits through the. vonne :tor line-relays 102 and 1.021 are then intvrri'lptld, and as a result the circuit established n' th thv connu-.tor releasemagia-t ,172 and lust-.selector hacha-@leaserelay 07 in series is destroyed: and at the saine tiuiv the lirat-selevtor release-1nagnot Si is dvinergized, at 'which time the said switrh A. is full)Y iustored. It is seen, thereiorv. that by the operation of restorinfhv the switrh-hool: 2 tho callin-gr suhsvriher, after he has rvveired a b is),7 signal. may return all of the ventral otliie apparatus that hv hais hrougiht into use to normal position. But if the Calling subscriber does not find the line busy and the connection over said lineis completed, as `previ msly described, by pressing the signaling-button 31 he signals the. valled subscriber. Grounding the Yertiealline-conductor by operating his signaling-button 31 causi s the Connect-or verticah line-relay 102 to or energized, and as a result, since the connevtor sid-sn'itcli-is in third position and sinvethe sido-switolr wiper 252 is therei ore in. engagement with the contact-point 207, the ringer-relav 20-'1 is energized. The rnergizing current basses from the ground terminal G through the. line-rel:ijf-springs 107 and 100 to th side.n switch-wiper 252, thence to the oon/caotpoint 207 and throl gh the ringvr-r.\.lav 201` cirruit-vontrolling-1@lay-springs 218n and 219 tothe battery-laid 2353111161 to the nongrounded terminal of battery B and to -ground G. VThe linger-relay 204 upon attracting its aruiat 1re 205 forces the ringe-rrulay-springs 200 and 201 aurair from the. normally engaging springs 20Sl and' 209 and onto the ringer-gelleratorprings 210y and 211.V The signaling vnrrent then passes onto the called subscribe"s lfie from the ringer- `sreuvrator 212, tht ougi the ringer-i`elay springs 211 and 205, sde-switoli-wiper 206, contact-point 270, oo nduotor 303, rotary-linewiper 150, rotary-nilrmal-Gonductor 274, rotary-lino-condnctor 304, condenser 305, ringerBOG, spring 307, switch-hook 308, vertical-line Conductor 309, vertical normalcondnctor 273, vertical-line-wiper 151, conduotor 310, Contact point 209, side-switch- .Wiper 205 and ring(rfrelay-springs 200 and 210 t0 the ringer-gfnerator 212. The subwhereby the` pole-changingrelay 213 and the circuit-controllingrelay 214 at the connector are magnetized. As soon as the circuitcontrolling-1'elay 214 becomes energiZcdthc springs 218 and 219 are forced apart and as a result the ringer-relay 204 and the releasemagnet 172, the rotary-magnet 173, the vertical-magnet 171`and the private-magnet 171 are disconnected from the battery-lead 233 and thus rendered inoperative. The polechanging-relay 213 upon attracting its a rm ature shifts the spring 215 ,from eonnectifm with the non-grounded terminal of the hat* terjvT B and into connection with the groundA ed (terminal of' battery B and current is thereby provided to the transmitter ot' the calling sub-station #100 for talking purposes, lThe current in the energizing circuit for the pole-changing and circuit-controlling relays 213 and- -214 fiows from the ground terminal G7 at the connector side-- switch to the contact-point 268, side-switchwiper 261, springs 224 and 223, relay 214, conductor 315, ringer-relay-sprmgs 203 and 206, sideswitchwipcr 265, vertical-linewiper 151, vertical-n0rmal-conductor 273, verticall'ineconductor 309, through springs'316 and 317, and the, springs 313 and "319, transmitter 312, primary Winding 313 of the induction-coil 311 to the rotary-line-- conductor 304, thence to the rotary-normal conductor 274, rotary-linewiper 150. sidi switch-wiper 266, ringer-relay-springs 307 and 209, conductor 298 and pole-changingrelay 213 to the non-grounded terminal of battery B and to ground G. The energia ing circuit for the transmitter at the calling sub-station #100 enables current to low from ground G9 through the pole-changingrelay-springs 217 and 215', vertical-line-relay 162, vertical-trunk-conductor 240, ver* ticalflinefwiper 39, of. the first-selector A,

sidesWitch-'wiper 130, vertical-lineconduc tor 225, springs 18 'and 17, and springs 19 and 20,signaling circuit spring 32, contact point 33, transmitter 301, primary winding 299 4of the induction-coil 300, rotary-lineconductor 226, side-switch-Wiper 131 of the first-selector A, rotary-linewiper 40, rotarytrunk-conductor 2111` rotary-line-relay 163 tothe iiongrounded terminal of battery B and to groundG. It will be noticed that the energizing current in this preceding circuit the passes through the vertical and rotary -linerelays 162 and 163 which are thereby energized, and as a result the trunk-releasesprings 169 and 170 are brought into contact, but since the circuit-control]ing-relay 214 is energized the energizing circuit that ordinarily would be set up throughthe connector release-magnet 172 and first-selector hackrelease-relay G7 in series is maintained ope-ned by the said circuitcontrollingrelay 214, Said circuit-controlling-relay having been once energized the release ofthe switch ing apiiaratus cannot take place until after said relay is deiinergizcd. for obvious reasons. Attention is also called to the fact that the line-rel:ly-springs 166 and 168 being kept against the groundfspring 167 both windings 221 and of the differential-relay 220 are energized. 'Through the Winding 221 a current flou-s from ground G through the springs 167 and 166 to said Winding 221 and thence to the non-grounded terminal of battery B and through the other winding 222 the current lloiis from ground Gi. through thc springs 7167 and 1,65 to the coil 222 and thence to the non-grounded terminal of battery B. rl`his relay, however, explained, when thus energized does not attract its armature 223. The tu'o subscribers` being thus connected, and their transinitters 301 and 312 l'iein'g in series with the primary windings 299 and ot' their respective induction-coils 300 and 3,14, and provided with talking current, and their receivers 7 and 311 being connected in series with the secondary windings 320 and 321 of their allotted induction-coils 300 and 314i-, the two subscribers in a manner n'elhknown to those skilled in the art may rar-,v communicate with each other. Con.- aertion having been established, if the called .subscriber restores his rei'civer 311 to the switch-hook the ringer 306 is restored across the line and the transmitter circuit is removed frein across the line from the instant that the springs 316 and 317, and 31S and 319 are forced apart. Thus the circl'litf-controlling and pole-changing relays 214 arid 213 are restored vand as a result the energizing current for ythe transmitter 301 at the calling sub-station is cut oli" and at the same time the operative magnets of the connector C are restored into connection Withthe nongrounded terminal of battery B." Then it the calling subscriber restores his receiver 7 he will ground both line-conductors and 226 and thercbyenergize the vertical and rotary line-relays 162 and 163 of the connector; and as a result the connector release-magnet 172 and iirst-selector back-release-relay 67 (which latter relay in turn -energizes the first selector release magnet 84) are all eergized in the manner already described.y This release is similar to the re-v lease described after the subscriber received the busy signal, the only diiferenceI being that the conneetor-switch-shaft 38 is rotated and must first return to normal rotary position before it falls to normal vertical position. If, however, the calling subscriber restores his receiver first` the release-circuits are' different. As the switch-hook descends the cam-arm 5 engages the ringer circuit spring 15 and forces the springs 17 and 18 apart and destroys the circuit that provides the transmitter 301 with current, which eircuit while established maintains the vertical and rotary line-relays 162 and 163 of the v'connector C energized, and as a result the sald line-relays are cle-magnetized. .As thesWitch-hook is lowered the ground-releasespring 3() is forced onto the vertical-linerelease-sprin -29 by the ca-m 4 and at once the vertical-llne-relay 162 is energized over well-known circuits. 166 is forced onto the spring. 167 a current passes through the winding 221 of the differential-relay 220, which relay then attracts its armature 223 and restores`the circuitcontrolling-ielay 214 and the pole-changingrelay `213, since the energizing circuit for these relays Ais controlled by the Vsprings 224 'and 225'l allotted to the differential-relay 220. At once the connector operative magnets are restored int-o connection with the non-grounded terminal of vthe battery B, and immediately after the switch-hook, having descended sufficiently, also groundsthe rotary-line-conductor 226 and thereby energizes the'rotary-Jine-relay 163 at the same time that the Vertical-line-r'elay 162 is enerized. As a result an energizing circuit is established through the connector releasemagnet 172 and the first-selector back-release-relay 67 that will restore the switches. It will be evident that while the calling subscriber `is making acall, and each time that the vertical or rotary line-relays of the connector C are energized singly, the differential-relay.l 220 is energized also but the energizing of said relay beforerthe' called subscriber has answered produces no eifect of consequence. It @will be noticed, furthermore, that during-the. release just described.

that takes place while the two subscribers lines are providedwith talking current, as

1soon as the rotary-line-relay 163' becomes energized, after the vertical-line-relay'- 162 has been energized, current will pass through the'other. side 222 `01E the differential-relay 220 #11i-neutralize the latterjbut the energizing o'f thel connector release-mag net 172 and the first-selector back-release.- relay 67 takes place so 'quickly when Vthe ,trunk-release,springs 169 and170 come 'into contact that the switches are restored before thearmature of the said differential-relay' 223 has had ,time ,to restore" the springs 224 As soon as the spring` of battery B. I1. will he evident that in such' a system the exchanges may be made to accommodate ten thousand subscribers if desired, in which :ase second-selector-switches would be used ind in any established connection, such as. the one shown in Fig. 1. The Second-Sele ctor would be located between the first-selectorA. and the connector C, as shown in Fig. 3. The second-selector is identical' with the first-selector A, save that the bridge-cut-o`-relay 62is removed, and, furthermore, no normal-conductors such as the conductors 244, 245 and 246 are provided, but iiistead from the spring 322 (similar to the back-release-relay-spring 69 of the first-Sele( tor A) 'a third or trunk-release-'conductor 323 extends to the firstselector private )bank-contacts 324, just as the third trunk-release-conductor 302 is connectedffrom the connector to the first-selector-banks. Wita the second-selector -in oircliit during a r1 lease, the connector` line-relays 162 and' 16.3 would close connection between the trunk release-spri'nufs 169 and 170, as shown in Fig. 1, and thereby energize the connector release-magnet 172 1n series with fs-,theV second-selector back-release-relay 325,

gize the rst-srleetor release-magnet, as 'is Well known.

During conversation and during thetemporary establishment of the talklng circuit between vany two subscribers, iheline-relays of the connector constitute the sole 'resistance for'bridging tha battery across the said circuit at the callfn side of the condensersfthat isnto say, fc r the Acircuit at th e right of the eondensers 271 andf272 (Fig. E ).l It will be understood, of" course, that oth er suitable inductive connections 'may -be substituted gior these conden'sers, for the broader purposes of my invention, and 'according to the r 4 uirements' ridging thebattery across j cuit at the called side of the said condensers. In this way, there will be only two relay windings in the circuit for charging the calling subscribers transmitter, and in a similar way there will only be two relay windings in the circuit for charging the called subscribers transmitter. The differential-relay of the connector has a local energizing circuit, as described, controlled by one 0f the line-relays. The sub-station devices for operating the releasing means of the connector comprise means for first opening the talking circuit,I means for then grounding one side of the circuit, and means for finally grounding both sides of the circuit. It will be seen that these three steps are all necessary when .the calling subscriber releases, but that only the rst step is necesi sary when the called subscriber releases.

The called subscriber can, ot' course, de energize the circiiitcontrolling-relay 214 by simply opening the line-circuit; but the call ing subscriber can only accomplish this operation through the medium of the dit erential-relay of the connector, and hence the necessity of the three operations when the calling subscriber releases.

The. connectors herein referred to, and in connection with which I have elected to illustrate my invention, may be of the general ty' e disclosed in Patent No. 815,176, issued Miiirch 13, 1906, to Keith, Erickson and Erickson.

Itwill be understood, of course, that the resistance Vof the various .relays and electromagnets can be readily adjusted to suit re uirements and with a View to obtaining the escribed method' of operation. F or exM ample, I have obtained good results by using relays and magnets having their resistance adjusted as follows: The rotary and vertical line-relays 163 and 162 500 ohms each; the vertical-magnet 171 G0 ohms; the rotary# magnet 173 60 ohms; the private-magnet 174i K 330 ohms; the'differential-relay windings v221 and 22-2 500 ohms each; the releasemag net 172 60 ohms; and the back-release-relay 67 of the first-selector ohm. The battery may be of 50 volts.

The relays '169J and 163, and 214 and 218 have sufficient resistance to regulate the supply of talking current to the sub-stations. In additiomthese four relays have suliicient self induction to enable them to act as impedance--coils for preventing the passage of voicc-currents through the battery which is bridged across thc talking circuit during conversation. t

1. In a telephone system, the combination of a temporarily established talking circuit :extending between calling and called subscribe-rs" nsub-stations, :i condenser in each side of said circuit, a centralizedsource of talking and switching current, subscriber controlled automatic switching machinery 'temporarily retained in position to maintain the circuit Afor talking purposes, said switching machinery provided with a pair of line-relays controllable only by the calling subscriber, the two windinvs of which constitute the only resistance ihr bridging the source of current across-the 'talking circuit at the calling side of said condensers, auxiliary circuits controlled by said relays, another pair of relays controllable by the called subscriber, the windings of which constitute the only resistance for bridgin the source of current across the talking circuit at the called side of said condensers,wux iliary circuits controlled by said last-mem tioned pairl of relays, and a fifth relay by which the calling subscriber controls the How of current to that part of the talking circuit allotted to the called sub-station. i

-2.111 a telephone system, the combination of a temporarily established talking circuit extending between calling and called, subscribers sub-stations, a condenser in each side ot said circuit, a centralized source of talking and switching current, subscribercontrolled automatic switching machinery temporarily retained in position to maintain the circuit for talking purposes, said switching machinery providedy with a pair of line-relays controllable only by the calling subscriber, the two windings of which constitute the only resistance for bridging .the source ot current across the talking circuit at the calling side of said condensers, auxiliary circuits controlled by said relays, another pair of relays controllable by the called subscriber, the windings of which constitute the only resistance for bridging the source of current across the talking circuit at the called side of said condcnsers, auxiliary circuits controlled byA said last-mentioned pair of relays, and aidiferentially wound relay by which the calling subscriber controls the loyy. of current to that part of the talking circuit allotted to the called suhstation.

3. In a telephone system, the combination of a temporarily established talkinf circuit extending between calling and culled sul scribers sub-stations, a condense.' in cach side of said circuit, a centralized source of talkin;r and switching current, subscrilusr-4 controlled automatic switching irrachincry tcniporuriiy retained in position to mail` tain thc circuit for tulkiu; r purposes, said .switching luiurhincry-plovidcd with a. pair l neutrahz constitute the only resistance for bridging the' source of current aereas the talking circuit at the called side of Said condcnscrs, auxiliary circuits controlled by said lastmentioned pair of relays, and a fifth relay by which thc calling subscriber controlathc flow of current to that part of the talking circuit allottedrto the called aublstation. SaidA fifth relay having two windings adapted to c each other when cnerglzcd in parallel. 1

4. Ina telephone system, thc combination of a tennicrariti mtablialaal talkingr circuit extending between calling and called Sub- ScribcrsA sub-stationa. a condenser in cach side of said circuit, a centralized source of talkingr and switching current, subscribercmitrolled automatic switching machinery temporarily retained in position to maintain the circuit for talkingr purposes, Said switching n'iachinery provided with a pair of lincrclays controllal'ilc only by the -alling suh- Flcriber, the two windings of which constitute thc only resistance for bridging thc source of current across thc talking circuit at the calling side of said condcnsers, auxn iliary circuits controlled by said relays, an-

other pair of relays controllable by thc called subscriber, the windings of which `c'0nstitute the only resistance for bridging the source of current across thc talking circuit atv the called side of said condcnscrs. auxiliary circuits conti-oiled by said lastinentioned pair of relays, and a fifth riclay by which the calling subscriber controls the fiow ot current to that part of thc talking circuit allotted to thc called sub-station, togcther with a trunk-rclcasc-circuit Yconjointly controlled by said linc-iclays and onc of said second pair of relays.

5. in a telephone system, thc combination ol a .ten'lporarily cstabliahcd lalkinpr circuit. cxtcnding between calling and called sub- .scribcrs sub-stations, a condenscr in cach side of said circuit, a ccntralizml .source of talking and switching currcnt, subscriber controlled aulon'iatic switching machinery tel'nporarily l'ctaincrl in position to maintain thc circuit tor talking purposes, said Switchingr nnlchincry provided with a pair of linc-rclays controllable only by the call?V ingsubscriber, lhc two windings of which i-.enistitutc thc onlir resistance for bridging the aourcc ol current across; thc talking-circuit at the callingr sidi ol aaid condcnscrs,

auxiliary circuito controlled by said relays, anothi-.r pair of rclays controllable by thccallcd aubscriboi, the windings ofvwhich conatilutc lhc. only resistance for bridgintgy the .#:ourcc ol current across the talking cir- 4cuit at thc callcd :ndo ot' said condonscra,

auxiliarycircuits controlled by said lasti'i'icritioncd pair of relays, anda h'l'th relay by which the calling subscriber ,conti-ots thc liow oi-- current to that part of thc talking circuit allotted to thc called Sub-station. together with ai cncrcizing circuit for said lii'lh rclay. sait cncrg'izing circuit controlled by one of said line-relays.

il. na tclcphonc si'ntmnJthe combination of a temporal' l \y cstabliahcd talking circuit extending bctwccn callingr and Iallcd subscribera sub-stations. a condcnficrv in` each side of sai" ci ruit, a c \ntraliV.cd source of talkirncY and s riti-hing current` subscribercontrollcd autnnatic .\'\\'iichiu;;fl inachil'icry temporarily ritaincd in position to niaintain thc circu't tor talking purpofais.Y said switching inaciincr broridcd with a pair oiE line-rclaya controllable onl \v by thc calling lauhscribcrA thc two windingl ot which constitute thc onl \Y rcsistancc tor briilpfinp,r the Source oi current acroan the talking;r circuit at thc calling sidc' ol. Said condcnscra, auxiliary circuit` controlled b v said rclays, another pair il rclaya conlrollablc by tho called subscrilcr. thc w'inilinnal ol' which constituir thc only rcaistancc for lu'idiriingr thc sourcc ol' rurlcnt acrosa thc talking circuit at thc ca lcd nido ol A*aid rondcnscrs, auxiliary circi its controlled by said laslnientioncd pair of relays. and alit'th rclay by which thc c illingl subscriber controls the tlow ol currcn .`to that part ol' thc talking circuit allottcd Yto lhc callcd lubgatatioin one ot said Second pair of rclays provided with nicans for controlling. tbc llow ot talkingr currcnt to thc c il`lingailbacribcfs aub-ntation.

T. ln :i tclcp ionc s rstcin, the combination olI a tclnporariliv cslablialaal lalkinnj circuit cxtcnding bctvccu collina' and callcd Subscrihcru" sailbslatiolia. a nondcnair in cachconstitutc thc only rcsiatalufc l'or bridging" the source ot c u'rcnt acrosnl lhc talkingr circuit at thc cal ing side ot said condcnscrs, au.\iliaryY circuits r'ontroll'cd by said relays, another pair fl rclayal controllable by thc called subscribi r, (hc indiaanl ot' which constitutc thc onlY rcristanco ior bridging! the Source of curr: nl, across ihr talking'crcuit 'at tho callcd cido ol' luuid cmulcnacrs. aukiliary circuits, controllcd by Aaaid lanldncntioncd pair ot rclaya, and a l|llcrcntiall wound relay bi which thc calling' aubscribci" controla the fl.w ol curi-cnt lo that. part ol.E

tho talkingr cin uit allottcd to thc callcd sub ata tion, ono o'fsald Second pairot rclayH. provided with moanaI 'l'or controlling` thc llow of talkingcorren; to thc calling subncribcfa slib-Statlon.

called side of said condensers, auxilia 8. Ina telephone system, the combination of la temporarily established talkin circuit extending between calling and cal ed subscribers sub-stations, a condenser in each side of said circuit, a centralized source of talking and switching current, subscribercontrolled automatic swiching machinery temporarily retained in position to main tain the circuit for talking purposes, said switching machinery provided with a pair of line-relays controllable only by the calling subscriber, the two windings of which constitute the only resistance for ridgingthe source of current .across the talking circuit at the calling side of said condensers, auxiliary circuits cont-rolled by said-relays,.another pair of relays controllable by the called subscriber, the windings ot' which constitute the only resistance for bridging thc source of current across the talking circuit at the called side of said condens-ers, auxiliary circuits controlled by said last-mentioned pair of relays, and a fifth relay by which the calling subscriber controls the flow of current to that part of the talking circuit allotted to the called sub-station, said lifth relay ha ving two windings adapted to neutralize each other when energized in piuL allel, one of said second pair of relays provided with means for controlling the flow of talking current to the calling subscribers sub-station.

9. In a telephone system, the combination of a temporarily established talking circuit extending between calling and called Subsciibcrs sub-stations, side of said circuit, a. centralized source of talking and switching current, subscribercontrollcd automatic switching machinery temporarily retained in position the circuit for talking purposes, said switching machinery provided with a pair of linerelays controllable only by the calling siib scriber, the two'windiiigs of which consti'- tute the only resistance for bridging the source of current across the talking circuit at ,the calling side of said condensers, auxiliary'circuits controlled by said relays, another pair of relays controllable by the called subscriber, the windings of which constitute 'the only resistance forV bridging the source of.

the talking circuit at the cirpair current across cuits controlled b said Vlast-niention of, relays, ing subscriber controls the How of current to that part of thetalking circuit allotted to the called sub-station, one of-said last-mentioned pair ot relays povidedmith Vmeans for shifting'or transposing the winding of' one of the line-relays from one pole of said source of current to the other.

10. In a telephone -system, the combination of a `pair of line-relays, a third relay,

release mechanism, a trunk-releasecircuit a condenser in eachl to maintain' and a li th relay by which the call-V conjointly controlled by said three relays, a differential-relay, an energizing circuit for said third relay, controlled by said differential-rela and a local venergizing circuit for said di erential-relay.

l l. .ln a telephone syst/ein, the combination of a pair oi' line-relays, a third relay, release mechanism, a` jointly controlled by said three relays, a dit ferential-relay, an energizing circuit for said third relay, controlled by said differentialrclay, and a local energizing circuit for said differential-relay, controlled by one oi said line-relays.

12. In a telephone system, the combination of a pair of line-relays, a third relay, release mechanism, a trunk-releasecircuit conjointly controlled by said three relays, a dil'eiential-ielay, an energizing circuit for said third relay, controlled by said ditlerential-rclay and an energizing circuit for said differential-relay, controlled by one of said line-relays.

I3. In a telephone system, the combina- .tion of a talkingr circuit, a connector pro* 'i-ided with a release mechanism, a releasean energizing circuit magnet, a release-relay, for said release-relay, including a portion of saidtalking circuit, a differential-relay controlling said energizing ciicuit, and a local circuit for energizing said differential-relay,

truuk release circuit con- In a. telephone system, the combina- I together with a line-relay controlling said local circuit. I

ll5. In a telephone systeimthc-combination. of -a talking circuit, a` connector pro-- vided 'with a release mechanism, .a releasemagnet, a release-relay, an energizing circuit for said release-relay, including a por- 'tion of lsaid 'talking circuit, a differentialrelay controllin said energizing circuit, and a local circuit or energizing said dileren* tial-relay, together wit a ine-relay controllin said local circuit, and n. trunk-re lease-circuit controlledby said line-relay and release-relay.

16. In a'telephone system, the combination of a trunk-release-circuit, line and re saidcir.

lease relays conjointly controllin cuit, a line-circuit flor energizing t e releaserelay, an additional relay for controlling said line-circuit, and a local circuit for energzing said additional relay.

17. In a telephone system, the combination of a talkin circuit, a connectorjprovided with a pair of line-relays, a dierential-relay, parallel. local circuits for the windings (if siiiil ilill'crcinifil,jrulzrre cnni triillcil 4lily mill liuc-ruining cliiscil when thc.

hit-turizi'rcicni'rwixril. unil il. i'irriiif-ciinlrnllcil l fi'ini uf siriil tulliing.circuit.`

llfln, u. ylclcpliniic syn-trui. 'the cinnbina- "'tiiin of 'il milking circuit, ii' connector pro- "rulcil rnitli :i rillusc uiccluuusiii, n rclcusgcf fieifciitiiiln'clny, siiiil! nnncrtor being also pruviilcdwith ai lnisy rclnsc circuit contrnllcd by sind Vrclcausc-rclny.

` `tii-ni of n tiilking circuit, :L conncctor proviilci] with-a rcleiisre inccliinisin, n release- -4 ningnef, i release-relay, :in `energizing cirrelay. cn'rilziblling said cncrgizing circuit, *.iinil :i lncnl circuit. for energizing Saul diff' fcrcntiul-rclny, together with 'x1 liiiercluy controlled by Suid relenSc-reilay.

2l. In r.' telephone systm'auJhga"cnrnbinn'e tiono `:i talking circuit` fr connector proriilcil `with. :i riflcnsn incchiinisifn, ir valeur@- iiiugncl., :i :fulmine-relai', ii-n cncrgizing, cir- (mit for snicl rclcnscfifvliiy, inclnilingizi pori tion nf suiil talking circuit,:rililfcrcnliiilrcliry controlling yniriilV @inrrgiliiiig circuit ir local circuit forcncrginiiigsind ilillirintuil- -circii it, mi trailing fils() 4prariiled withal biisyf'rclens'e *cir* .4 un. iliilguinntir -1 windings of sail dillcrcutiail-rclny, com tiiiillil by Miiflli ic-reln closccl when the laitlvr :rrn cnbrgizeil, i circuit colitrolledwby wur ilil'l'urcutiirl-i clin?, :including ii `portim'i n'l' .-n'iil iiilliingici fcuit, Suid' connector being nlm pruriilcil with ii` luigi" release "circuit,

:nul -rlvcLi'o-iiiiigi'cts cnnjn'intly controlling `tinn nin tiilliing circuit., :i connector prof liittcr :ire-energized, :i circuit c oiilfrolliil by f lii'iil rlillfcrcntinlioilily, sn'id conncctnr Being :liso 14 proi'lgd nillr :i busy rclwisjc circuit, norniiillr open :ii il Anorn'izilfl'y closcil :nritclv` noint in s :iiil buiy releasey circuit. und clccf tifo-inuggucls for npcrziting Suid switchpoints und thuriby ccnjointly cmilrolling 25. 'in il tiilcpl mic "H iistcinrthc combinaitinn if ii talkin; circuit, ;i "connector proviilvil' with :i 1mi" 0l' linc-rcliiys, :i fliffcrm liul-rcliri', purullfl local circuits. 4'for the windings' @Vsii il 'ilillcrdnlinl-relfiy, con4 v triillcil hy siii-l linc-rel'aiys, 4rinsed-when'the rziiiil glill'crinl'izilmlny, includ ing :i portion of priiriiluil with 'ir liny Vrcl'cnsc. circuit, nor; inrillmr olnn 'unil normallyl closed ,switchninllli' connecte: 1min tifs nil lmtigwyF moans for connecting; thc nlilivr tcrinlnils,nffsnicl windingsm-ivitl1- il?. 'In .ngtul'ph'fnui sysfcinijth combinai tn nriil u hnttrri-f haring nnc poli, grouniled',

su iil rrlny.

the circuit for talking purposes, said switching machinery provided with a pair of linerelays controllable only by the calling subscriber, the two windings of which constitute the only resistance for bridgin the source of current across the talking circuit .at the calling side of said condensers, auxih lary circuits controlled by said relays, means controlled by said auxiliary circuits haring vertical motion to select a group and rotary motion to connect with the desired line in the selected group, another pair of relays controllable by the called subscriber, tho windin" oi' which constitute the only resistauc bridging.,r the source of current :irri s the. talking circuit at the called side of :said condcnsers, auxiliary circuits controlled by ,ii/l last-mentioned pair of relays, and a i' l; relay by which the calling sub scrihor controls the. flou' of current to that. part oi the talkingcircuit. allotted to the rulli-d silbslulifiii,

il), ln :i telephone system, (he combination :i temporarily established talkingY i'ii'f'uii rxtruding between rallincr and called riesci-ii; s` substations, a rondom-'er in each fide oi id circuit` a centralized source of talkin;lr :ind switchin, ,fY current` subscribercont-rolled automatic switehinbr machinery temporarilv retained in position to main- 'reuit for talking purposes, said machinery prorided with a pair of lil... u vs controllable only by the callim,Y subscriber, the two windings of which constitute the only resistance ioidbridging the source of currentacross the talking: circuit :it the calling,r side of said coudenrers, auxiliary circuits controlled by said relays, means controlled by said auxiliary circuits having vertical motion to select a rgroup und rotary motion to connect with the desired line in the selected group, another pair of relays controllable by the called subscriber, thc windings of which constitute the only resistance for bridging the source of current across the talking circuit at the called side ot said condcnsers, auxiliary circuits con trolled by said last-mentioned pair ot relays, and ii dillcrentiallyewound relay by which the calling subscriber controls the llow of current to that part of the talking circuit allotted to the called substation.

" 30. In a telephone system, the combina tion of a temporarily established alking circuit extending between calling ill called subscribers subst-ations, a. condenser in each side of said circuit, a centralized source of talking and switching current, subscribercontrolled automatic switching machinery temporarily retained in position to maintain the circuit for talking purposes, said switching machinery provided with i1 pair of linerelays controllable only by the calling subscriber, the two. windin s of which constitute the. only resistance or bridging the source of current across the. talking eircuit ut the calling. side of said condcusers` auxiliary circuits controlled b said relays. inea'ns controlled by said auxiliary circuitsl having vertical motion to select n. group and rotary motion to connect with thedesired line in the selected group, another pair of relays controlliible by the called subscriber, th.= windings of" which constitute the onlir resistance for bridging the soii'ree'of current 'l subscribers substations a condenser in euch sido of said circuit` a centralized source of talking and switching current, subscribercoutrollcd aui`mali 1 switching machinery.' temporarily retained in position to iiiantain the circuit for talking purposes, said switching machinery provided with a pair of line-relays controllable only by the calling subscriber, the two windings'of which constitute the only resistance for bridging the source of current across the talkingy circuit at the culling side of said condensers, auxiliury circuits controllable by said relays, means cout-rolled by said auxiliary circuits having vertical motion to select :i group .and rotary motionl to connect with the desired linoin the selected "group, :mother pair of relays controllable by the called subscriber. the windings of which constitute the only' resistance for bridgirig the source of current ai'. lss the talkin;r circuit 'at the called side of said condensers, auxiliary circuits controlled b v said last-mentioned pair of relays', and a fifth relay by which the calling si1bscriber controls the flow of current to that part of the talking circuit allotted to the called substation, together with a trunk release-circuit onjointly controlled br' said liuc-relays and one of said second pair of relays. 32. In a telephone system, the combination of a temporarily established talking circuit extending between culling and called subscribers substations, a condenser in euch side. of said circuit, a centralized source of talking and switching current, subscribercontrolled .automatic switching machinery temporarily retained in position-to maintain the circuit for talking purposes, slid switching machinery provided with; pain of hnere-lays controllable only by the calling sub scriber, the two windings of which constitute the only resistance for bridging the source ot eurrciit across the talking circuit at-'thc calling side of said eoudensers, auxiliary, circuits controlled by said relays, ineans controlled b): said auxiliary circuits having vertical motion to select a group and rotary motion to connect with the desiredline in the selected group, another pair of relays 'taintrollable by the. called subscriber, tlie windings of which constitute the only 1; resistance-'tor bridging thc source ot'. ai1rc1it across the talking circuit yat the called sideof said condensers, auxiliary circuits conitrolledby said lastlilneutioucd pair of relays, and a fifth relay by which the calling subscribercontrols the liow oi current to that part of' thc talking circuit allotted to the called substation, together with an encrigizing circuit for said fifth relay, said cn'ergiziiig circuit controlled by one of said line relays.

33. ln 4a telephone system, the coinbination of a temporarily established talkingl cirjcuit extending between calling and called subscribers? suhstations, a condenser in each side of Asaid circuit, a centralized source ofV talking and 'switching current.-subscriber controlled .automatic switching machinery v ltemporarily retained in position to maintain the circuitior talking purposes, said switch 80 ing machinery provided with a pair of linerelays controllable onl-y by the calling' subscriber, the two windings of which constitute athe4 only .resistance for bridging thesourcc, of current across the talking circuit at the 85- calling side ci said condensers, auxiliary circuits controlled by v said relays, means controlled by said auxiliary circnitsharing -iertieal inotion to select a group and rotary motion to connect with the desired line in 40 the selected group, another pair of relays controllable by the called subscriber, the windings of which constitute 4the only resistmance. for bridging 'the source of current across the talking circuit at the called side 460i said conflensers, auxiliary circuits con trolled b f said last-inent'ioned pair of relays, anda fi `th relay -by which .the calling subv .,scriber controls the 'flow of'current to that part `of' the talking circuit allotted to' the p56 called substatioin' one of said second pair of' -l Vrela-ys provided with: means forcontrolling l the flow, of talking current to the ealhiig fysubscribers substation` f B4. Ina telephone systeinr-.the coinbiua i tiono'f ii'temporarily established talking 4 cire it extending between'callingl andV called i sub cribers substations, a condenser in each s`ide of -said cireuitfa centralized source 'of talkin 'and switching current, subscribercontrolled-automatic switching machinery ytemporarilyretfjxinied 4in position to .maintain t'liefcircuit 'fortalking purposes, saidswitch- 'king machinery ovidedf-with 'i pair of linere ays "controlla .55 seri'ber, ,the two windings' 4of which consticircuit for talking purposes, said switching le onlyiby' the calling sub .the windings ot which constitute the only resistance for br dging the source of currentacioss the talk ng circuit at the called side of said condor sers, auxiliary circuits controlled by said ast-mentioned )air of relays, and a differentiallyavound re ay by which the calling sul scriber controls the. flow of current to that part of the. talking circuit allot-ted to the :alled substation, one of said second pair oi relays provided with means 'Foi'.controlling the liow of talking current t'o thc calling s ibscribers substation.

Elfi. ln a telcl: hone system, the combination oi' a` temporali y established talking circuit extending bctv cen calling and. called sub'- seribers" substa ions, a condenser in each side of said circuit. a centralized source of talkingr and s\\'it. l,ug current, subscriber-controlled automav ic switching machinery teni-4 porarily retain d in position4 to maintain the 9`5 unichinezr pro jidcd with a pair of line-relays controllatle only by the vcalling subscriber. the two windings of which constitute the only resist in'ee for bridging the source oi current across the talking circuit-at the' 100 calling" side of laid condensers, auxiliary circuits controlled by said relays, means controlled by said auxiliary circuits having vertical inotiol to select a group and rotary motion to connect with the desired lino in the selected gioilp, another pair of relays controllable bf the called subscriber, the windings of y hioh constitute the ,only7 resistance for b1 idging the source `of current across the talking circuit at the called side of 11e,

said condenser: auxiliary circuits controlled by said last-mentioned pair of relays, and a lifth relay by which the calling subscriber controls the How of currentto that part of the talking cir .uit vallotted to the called sub-4 115 station, saidifth relay haj-'ingtwowindlugs adapted io neutralize ca clr other when energized 1n p: ,ralle1, one of said second pair- 4of relays provided withmeans for control'- ling the. flow. t f talkingcu'rrent to the cal1' 120 ing vsubscriber s substation. l

8G, In a tele v)hone s'vstein,.tl1e combination ot a temporal' ly4 established talking circuit extending bet'veen callingand calledsnbsoribers subst: tions, l`a condenser in c'aeh side 125 'of said circuit, a centralizedsource of talking and switching current, subscrilier-con` trolled autom: tic switching machinery tern-` porarily reta-ii ed in position to nn\intainthe circuit tor tal ting purposes, said switching 132) tute the only resistance for 'bridging the-A machinery provided with a pair of line-relays controllable only by the calling subscriber, the two windings of which constitute the only resistance for bridging the source of current across the talking circuit at the calling side ot' said condenscrs, auxiliary circuits controlled by said relays, means controlled by said auxiliary circuits having vertical motion to select a group and rotary motion to connect with the desired line in the selected group, another pair of relays controllable by the called subscriber, the windings of which constitute the only resistance for bridging thc source of current across the tall ng circuitat the called side of said condensers, auxiliary circuitscontrolled by `said lastaneutioncd pair of relay 'and a lifth relay by which the calling sub. iber controls the low of current to that part of the talking circuit allotted to the called sub station, one of said last-mentioned pair of relays provided with means for shifting or transposing the winding of one ol' the linerelays from one pole oi' said source of current to the other.

37. ln a telephone system, the combination of a temporarily established talking circuit extending between calling and called subscribers substations, a condenser in each side of said circuit, a centralized source of talking and switching current, subscribercontrol'led automatic switching machiner' temporarily retained in position to maintain the circuit for talking. purposes, said switch ing machinery provided with a. pair of linerelays controllable only by the. calling subscriber, the two windings of which constisource of current across the talking circuit at the calling side of said condensers, auxiliary circuits controlled by said relays, means controlled by said auxiliary circuits ha ving'vertical motion to selecta` group and rotary motion to connect with the desired line in the selected group, another pair of relays controllable by the called subscriber, the windings of which constitute the only resistance for bridging thc source of current across the talking circuit at the called side of said condensers, auxiliary circuits controlled by said last-mentioned pair of relays, and a. fifth relay by which the calling subscriber controls the llow of current to that part of the talking circuit allotted to the called substation, both pairs of relays energized and provided with armatures which remain attracted during conversation.

38. In a telephone system, the col'nbination of a temporarily established talking circuit extending between calling and called subscribers substations, a condenser in each side of said circuit, a centralized source of talking' and switching current, subscribercontrolled automatic switching machinery temporarily retained in position to maintain the circuit for talking purposes, said switching machinery provided with a pair ol' linerelays controllabh` only by the calling subscriber. the two windings oi' whiclrconsttule the only resistance for bridging the source of current across the 'talking circuit at the calling side of said condensers, auxiliary circuitscontrolled by said relays, means controlled by said auxiliary circuits having vertical motion to select a group and rotary moliou'to connect with the desired line in il-nselected group, another pair of relays controllable h v the called subscriber, the hulings ol' which constitute l'heonly resislanre l'or bridging the source of current across the talking` circuit at the called side ol' said condensers. auxiliary circuits con- Ll'ollcd by said last-lncntiolufd pair of relays, and a dill'creutially-wound relay by which thc calling subscriber controls the llow ol current to that part. of the talking circuit allotted to the called substatit'n,= both pairs oi relays energized and provided with arlnutures which remain attracted during ronvrrsation.

39. ln a telephone system, the combination of a temporarily established talking circuit extending between calling and called subscribers substations, a condenser in each side of said circuit, a centralized source of talking and switching current` sulscrilar-controlled automatic switching machinery teniporarily retained in positionlo maintain the circuit for talking purposes, said switching machinery provided with a pair o linerelays controllable only by the calling` subscriber, the two windings ol'4 -which constitute the only resistance for bridging the source of current across thetalking circuit at the callingr side of said eoiulenscrs, auxiliary circuit-s controlled by said relays, means controlled by said auxiliary circuits having vertical motion to select a group and rotary motion to connect with the desired line in the select-ed'group, another pair of relays controllable by the called subscriber, the windings of which constitute the only resistam-.e for bridging the source of current across the talking circuit at the called side of said condensers, auxiliary circuits controlled by said last-mentioned pair of relays, and a lit'th relay by which the calling subscriber controls the llow of current to that part of the talking eircuit-allotted to the called substation, said lifth relay having two windings adapted to neutralize each other, when energized in parallel, both pairs of rclays energized and provided with arn'iatnres which remain attracted during conversation.

4,0. In a telephone system, the cannbination of a temporarily established talking circuit extending betwcel'i calling and called subscribers substations, a condenser in cach side of said circuit. a centralized source ol talking and switching ctn-rent, subscriber-con- 

